Thread pulling device



W. DREHER THREAD PULLING DEVICE April 28,1959

I 2 She ets'-Sheet 1 Filed Dec. 23, 1955 INVENTUE Wilhelm DREHER 7 Mum-4.4M

April 28, 1959 w. DREHER 2,883,954

THREAD PULLING DEVICE Filed Dec. 23, 1955 INVENTOR W/Lf/fl/W Diff/t7? 2 Sheets-Sheet 2 United States Patent THREAD PULLING DEVICE Wilhelm Dreher, Kaiserslautern, Germany, assignor to G. M. Pfatf A.-G., Kaiserslautem, Germany, a corporation of Germany Application December 23, 1955, Serial No. 555,164

Claims priority, application Germany December 24, 1954 4 Claims. (Cl. 112242) The invention relates to sewing machines, and relates more particularly to sewing machines of the type that have means for thread severing for instance at the end of the sewing cycle and for pulling at about the time of thread severing a sufiicient length of thread off the spool to enable the sewing needle at the subsequent resumption of sewing operation to form a stitch. Still more particularly, the invention relates to such thread pulling devices for sewing machines. The invention is particularly applicable in connection with specialized industrial sewing machines, but its use is not restricted thereto as it may be used with all kinds of sewing machines.

Desirable features of thread pulling devices include simplicity of actuation and reliability of operation, and these are generally found in thread pulling devices now in use. Present thread pulling devices, however, are deficient in that they either are quite complicated, or do not provide for adjustable preselection to pull off the spool amounts of thread of varying lengths.

It is therefore among the objects of the invention to provide a thread pulling device of simple construction that permits to pull thread of varying lengths off the spool, permitting selective adjustment of the desired thread length.

The foregoing and other objects of the invention will be best understood from the following description of an embodiment thereof, reference being had to the accompanying drawing, wherein:

Fig. l is a fragmentary perspective view of a sewing machine head from which the side cover has been removed, showing a thread pulling device in accordance with the invention, the parts of the device being illustrated in position during sewing machine operation;

Fig. 2 is a fragmentary perspective view similar to Fig. 1, but showing the parts of the device in position during the initial phase of lifting of the presser bar;

Fig. 3 is a fragmentary perspective view, similar to the preceding views, but showing the parts in position during thread pulling;

Fig. 4 is an elevational view, partly in section, taken on line 44 of Fig. 1; i

Fig. 5 is a detail view to an enlarged scale showing the regulator mounted on its guiding support member;

Fig. 6 is a detail of the sleeve for actuating the regulator; and

Fig. 7 is an exploded view of the regulator and its supporting guide member.

In carrying the invention into eifect in one of the embodiments, which has been selected for illustration in the accompanying drawing and for description in this specification, and referring now particularly to Fig. 1, there is provided a sewing machine head 1 in which there are reciprocably guided for linear vertical movement a needle bar 2 and a presser bar 3. The needle bar 2 cooperates in conventional manner with a thread take-up lever 4. The thread 5 runs from a spool (not shown) first to a guide 6, passes thereafter between tension discs 7 of a thread tensioning mechanism 8, then is engaged by a thread control spring 9, thereafter is engaged by a regulating hook 10 of a thread regulator 11, then passes through, an eyelet 12, thereafter passes through a hole that is formed in the take-up lever 4, thence passes again through the eyelet 12, and is thereafter engaged by the needle 13.

A presser foot lifter 14 is drivingly connected to the presser bar 3 by means of a sleeve 16 which is slidable on the presser bar 3 and a guide member 15 which is secured to the presser bar 3. A presser foot compression spring 17 helically surrounds the presser bar 3 and bears with its lower end against the top surface of the guide member 15. The tension of the spring may be varied by means of an adjusting screw 18 which is threaded in the head 1.

The thread regulator 11 is pivoted to the guide member 15 by means of a screw 19. A spring 20 engages with one end a recess 21 that is formed on the underside of the regulator 11, and slidingly engages with the other end a hole that is formed in a nose 22 of the guide member 15. The spring 20 urges the regulator 11 to turn about the axis of the screw 19 upwardly into a horizontal position (Fig. 1) against the oppositely acting gravitational forcewhich tends to turn the regulator 11 about said axis downwardly.

A pin 23 projects from the regulator 11, and the spring 20 causes the pin 23 to abut against the top surface of the guide member 15, thereby limiting the upward turning movement of the regulator 11 under the power of the spring 20 to a substantially horizontal position at right angles to the presser bar 3. The regulator 11 has below its axis of rotation a recess 24 (Fig. 2) which includes a slanting surface 25 that slopes downwardly towards the rear and adjoining which there is an upwardly inclined surface 26 (Fig. 1) forming an angle with the slanting surface 25.

In the front wall of the head 1 there is formed a vertical slot 27 which has an upper edge 28. The hook 10 of the regulator 11 projects through the slot 27, and the upward movement of the hook 10 is limited by the edge 28 that acts as a stop. The downward movement of the hook 10 is limited by a stop such as a projection 29 that forms part of a dog 30, which is adjustable as to its height. The dog 30 has an elongated hole 31 through which there extends a screw that fastens the dog 30 to the head 1. Upon loosening of the screw, the dog 30 may be lifted or lowered, and then the screw tightened again. The projection 29 extends into the slot 27, and its position within the slot 27 may be varied by means of the aforedescribed adjustment of the dog 30.

The sleeve 16 includes a projection 32 that has a horizontal upper edge 33 off-set from a raised nose 34, the inner edge of which is disposed substantially at right angles relative to the rear edge of the regulator 11.

A compression spring 35 (Fig. 1) is disposed between the guide member 15 and the sleeve 16 and serves to keep the sleeve 16 as well as the lifter 14, which is in driving connection with the sleeve 16, in the lowermost position when the presser bar 3 is lowered, to prevent rattling of the parts during the operation of the sewing machine.

The operation of the above described thread pulling device is as follows.

During the operation of the sewing machine, the presser bar 3 will be in the lowermost position, and the thread 5 will describe the path as shown in Fig. l. The regulator 11 will be held in substantially horizontal posi tion (Fig. 1) owing to the actions of the spring 20 and of the pin 23, that abuts against the upper surface of the guide member 15 of the presser bar 3. In this normal sewing machine operating position, the upper edge of the hook 10 of the regulator 11 will be spaced below the edge 28 of the slot 27 for a distance suflicient so that the regulator 11 may partake in the straight up and down movements of the presser bar 3 during the sewing of material that has uneven thickness, without the occurrence of any impact between the hook and the edge 28. The compensation for the additional thread required upon change in thickness of the material worked on is accomplished in a known manner, in that the thread control spring 9 needs to pull up the larger amount of thread needed with the thicker material only to a correspondingly lesser extent.

Upon lifting of the sleeve 16 (Fig. 2) by means of the lifter 14, the nose 34 of the projection 32 thereof will abut against the inclined surface 26 of the regulator 11. Further lifting of the sleeve 16 will cause raising of the presser bar 3, and therewith of the regulator 11 in its entirety until the hook 10 thereof abuts against the edge 28 of the slot 27 in a predetermined position of the presser bar 3. Owing to this abutment, the regulator 11 will be turned downwardly about the axis of the screw 19 during the ensuing continued raising of the presser bar 3. During this downward turning of the regulator 11, the inclined surface 26 thereof will slide past the nose 34 (Fig. 3) and the spring 17 will cause the continuation of the downward turning of the regulator 11 until the hook 10 will abut against the projection 29 of the dog 30. During the last mentioned downward turning phase of the regulator 11 under the impact of the spring 17, the hook 10 will pull a length of thread 01? the spool. The sleeve 16 and the regulator 11, by means of the surface 33 and nose 34 of the sleeve 16 and the surfaces 25 and 26 of the regulator 11 form a self-releasing clutch.

By appropriately adjusting the position of the dog 30, and thereby of the projection 29, there will be adjusted the length of the arcuate path of the hook 10 and thereby there will accordingly be adjusted the length of the thread pulled. The dog 30, and therewith the projection 29, may also be so positioned, if desired, to inactivate the thread pulling device, relegating the latter to the function of compensating only for the changing thread requirements caused by changes in the thickness of the material.

The thread pulling device in accordance with the invention may be mounted on any sewing machine.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

Having thus described the invention, what I claim as new and desire to be secured by Letters Patent, is as follows:

1. In combination, a thread pulling device in a sewing machine of the type having a machine head, a presser bar supported for vertical reciprocating movement in said machine head associated with a manipulating device, and a needle bar including a needle supplied with thread along a path externally of said machine; said thread pulling device comprising an upwardly extending slot in said machine head defining an abutment, a regulator including a pivot member supported for tilting movement on a guide member mounted on said presser bar, said regulator extending through said slot to engage said thread, a biasing spring retaining said regulator in a predetermined angular position relative to said presser bar, means operatively related to said manipulating device adapted to move said regulator vertically with said presser bar, means including said abutment adapted in cooperation with said manipulating device to tilt said regulator about said pivot member, and means limiting the tilting movement of said regulator.

2. In combination, a thread pulling device in a sewing machine of the type having a machine head, a presser bar supported for vertical reciprocating movement in said machine head associated with a manipulating device, and a needle bar including a needle supplied with thread along a path externally of said machine; said thread P 1 ing device comprising an upwardly extending slot in said machine head defining an abutment, a regulator including a pivot member supported for tilting movement on a guide member mounted on said presser bar, said regulator extending through said slot to engage said thread, a biasing spring retaining said regulator in a predetermined angular position relative to said presser bar, means operatively related to said manipulating device adapted to move said regulator vertically with said presser bar, means including said abutment adapted in cooperation with said manipulating device to tilt said regulator about said pivot member, and means limiting the tilting move ment of said regulator, said limiting means including stops near the slot ends, one of said stops being defined by said abutment and the other being adjustably positionable, said regulator during the lifting of said presser bar abutting against one of said stops in a predetermined position of said presser bar, the distance between said stops determining the length of thread to be pulled by said regulator.

3. In combination, a thread pulling device in a sewing machine of the type having a machine head, a presser bar supported for vertical reciprocating movement in said machine head associated with a manipulating device, and a needle bar including a needle supplied with thread along a path externally of said machine; said thread pulling device comprising an upwardly extending slot in said machine head defining an abutment, a regulator including a pivot member supported for tilting movement on a guide member mounted on said presser bar, said regulator extending through said slot to engage said thread, a biasing spring retaining said regulator in a predetermined angular position relative to said presser bar, means operatively related to said manipulating device adapted to move said regulator vertically with said presser bar, means including said abutment adapted in cooperation with said manipulating device to tilt said regulator about said pivot member, and means limiting the tilting movement of said regulator, said guide member being secured to said presser bar, and having an upper surface, said regulator including a pin abutting against said surface when said regulator is in a normal position wherein it extends at a fixed angle to said presser bar, and said biasing spring urging said regulator into said position.

4. In combination, a thread pulling device in a sewing machine of the type having a machine head, a presser bar supported for vertical reciprocating movement in said machine head associated with a manipulating device, and a needle bar including a needle supplied with thread along a path externally of said machine; said thread pulling device comprising an upwardly extending slot in said machine head defining an abutment, a regulator including a pivot member supported for tilting movement on a guide member mounted on said presser bar, said regulator extending through said slot to engage said thread, a biasing spring retaining said regulator in a predetermined angular position relative to said presser bar, means operatively related to said manipulating device adapted to move said regulator vertically with said presser bar, means including said abutment adapted in cooperation with said manipulating device to tilt said regulator about said pivot member, and means limiting the tilting movement of said regulator, said regulator having below its pivot axis a downwardly and rearwardly slanting surface and an upwardly and rearwardly inclined surface adjacent said slanting surface, a sleeve disposed below the pivot of said presser bar and being slidable on said presser bar and including a projection having an upper surface off-set from an upwardly extending nose of said projection, and resilient means pressing said regulator, said nose normally abutting against said inclined surface taking up the pressure of said resilient means when said References Cited in the file of this patent UNITED STATES PATENTS .Diehl Dec. 1, 1903 Hohmann Aug. 11, 1925 Prange Mar. 26, 1929 

